Index: include/llvm/Support/KnownBits.h
===================================================================
--- include/llvm/Support/KnownBits.h
+++ include/llvm/Support/KnownBits.h
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file contains a class for reprsenting known zeros and ones used by
+// This file contains a class for representing known zeros and ones used by
 // computeKnownBits.
 //
 //===----------------------------------------------------------------------===//
@@ -19,7 +19,7 @@
 
 namespace llvm {
 
-// For now this is a simple wrapper around two APInts.
+// Struct for managing the known zeros and ones of a value.
 struct KnownBits {
   APInt Zero;
   APInt One;
@@ -36,6 +36,56 @@
            "Zero and One should have the same width!");
     return Zero.getBitWidth();
   }
+
+  /// Returns true if there is conflicting information.
+  bool hasConflict() const { return Zero.intersects(One); }
+
+  /// Returns true if there is no conflicting information.
+  bool isValid() const {
+    assert(Zero.getBitWidth() == One.getBitWidth() &&
+           "Zero and One should have the same width!");
+    return !hasConflict();
+  }
+
+  /// Returns true if we know the value of all bits.
+  bool isComplete() const {
+    assert(isValid() && "KnownBits conflict!");
+    return Zero.countPopulation() + One.countPopulation() == getBitWidth();
+  }
+
+  /// Returns the value when all bits have a known value. This just returns One
+  /// with a protective assertion.
+  const APInt &getValue() const {
+    assert(isComplete() && "Can only get value when all bits are known");
+    return One;
+  }
+
+  /// Returns true if this value is known to be negative.
+  bool isNegative() const { return One.isSignBitSet(); }
+
+  /// Returns true if this value is known to be non-negative.
+  bool isNonNegative() const { return Zero.isSignBitSet(); }
+
+  /// Truncate the underlying known Zero and One bits. This is equivalent
+  /// to truncating the value we're tracking.
+  void trunc(unsigned BitWidth) {
+    Zero = Zero.trunc(BitWidth);
+    One  = One.trunc(BitWidth);
+  }
+
+  /// Zero extends the underlying known Zero and One bits. This is equivalent
+  /// to zero extending the value we're tracking.
+  void zext(unsigned BitWidth) {
+    Zero = Zero.zext(BitWidth);
+    One  = One.zext(BitWidth);
+  }
+
+  /// Sign extends the underlying known Zero and One bits. This is equivalent
+  /// to sign extending the value we're tracking. 
+  void sext(unsigned BitWidth) {
+    Zero = Zero.sext(BitWidth);
+    One  = One.sext(BitWidth);
+  }
 };
 
 } // end namespace llvm